The invention is directed towards tetrahedral and pseudo-tetrahedral late transition metal polymerization catalyst complexes and their use in forming homopolymers from olefins or polar monomers and copolymers from olefins and polar monomers.
Polymers and copolymers may be formed from olefinic monomers by using transition metal metallocene catalyst technology. This well-known technology uses catalysts containing early transition metal atoms such as Ti and Zr.
Even though polyolefins formed by such metallocene catalysts posses enhanced properties over polyolefins produced by conventional Ziegler-Natta catalysts, further improvements in properties such as wettability and adhesiveness may be possible. It is believed that including polar monomers in an olefinic polymer or copolymer would improve wettability and adhesiveness in those materials. Unfortunately, polar monomers tend to poison early transition metal catalysts.
Certain late transition metal complexes of palladium and nickel incorporate some polar monomers. However, such catalyst systems are costly. Also, the polymers so produced are highly branched (85-150 branches/1000 carbon atoms) and the functionalities are not in the chain but at the ends of branches. Consequently, they are limited to polar monomer contentsxe2x89xa6about 15 mol%. Another disadvantage of these systems is that they incorporate only a limited number of polar monomers (e.g. alkyl acrylates and vinyl ketones). Methyl methacrylate and n-butyl vinyl ether are mildly inhibiting or inert.
Certain functional ethylene copolymers can also be made by free radical polymerization. In commercial practice, these materials also have significant short-chain and some long-chain branching (E. F. McCord, W. H. Shaw, Jr. and K A. Hutchinson, Macromolecules, 1997, 30, 246-256). Furthermore, some functional monomers (e.g. n-butyl vinyl ether) do not readily incorporate under free radical conditions (K. W. Doak, Encyclopedia of Polymer Science and Technology, 2nd Ed. H. F. Mark, Ed John Wiley and Sons, New York, 1986, Vol. 6, pp 387-429.
Consequently, there remains a need for a polymerization catalyst capable of forming olefinic polymers and copolymers and that are effective polymerization catalysts in the presence of polar monomers.
In one embodiment, the invention is a substantially linear copolymer represented by the formula: 
where A is a segment derived from an acyclic aliphatic olefin of 2 to about 20 carbon atoms;
R is H or CH3;
X is xe2x80x94OR1 or xe2x80x94COOR1;
R1 is an alkyl group of 1 to 24 carbon atoms; and Y is from about 0.02 to about 0.95
One embodiment of the invention comprises comprises a substantially linear copolymers having the formula: 
where A is a segment derived from an acyclic aliphatic olefin of 2 to about 20 carbon atoms; R is H or CH3; x is xe2x80x94OR1 or xe2x80x94COOR1; R1 is an alkyl group of 1 to 24 carbon atoms and y is from about 0.02 to about 0.95 and preferably y is from about 0.18 to about 0.85.
These copolymers have polar functional monomer segments, 
which are substantially in the chain rather than at ends of branches.
In the case where xe2x80x94Axe2x80x94 is a polymer segment derived from ethylene, the branch content of which is below about 15 branches/1000 carbon atoms, for example from about 0.5 to less than 15 branches.
In another embodiment, the invention comprises a substantially linear copolymer having a polymer chain of the formula: 
where A is a segment derived from an acyclic aliphatic olefin of 2 to about 20 carbon atoms. R is H or CH3. X is xe2x80x94OR1 or xe2x80x94COOR1. R1 is an alkyl group of 1 to about 24 carbon atoms and y is from 0.18 to 0.85.
In yet another embodiment, the invention comprises a substantially linear copolymer having a polymer chain comprising the formula: 
where A is a segment derived from ethylene. R is H or CH3. X is xe2x80x94OR1 or xe2x80x94COOR1. R1 is an alkyl group of 4 carbon atoms and y is from 0.18 to 0.85.
In another embodiment, the invention comprises a substantially linear copolymer having a polymer chain comprising the formula: 
wherein y 0.02-0.95.
In another embodiment, the invention comprises a substantially linear copolymer having a polymer chain comprising the formula: 
wherein y=0.02-0.95.
In another embodiment, the invention comprises a substantially linear copolymer having a polymer chain comprising the formula: 
wherein y=0.02-0.95.
In another embodiment, the invention comprises a substantially linear copolymer having a polymer chain comprising the formula: 
wherein y=0.02-0.95.
The catalyst used in the process to form this invention is a complex having the formula LMX1X2, wherein L is a nitrogen-containing bidentate ligand represented by the formula:
[AZAxe2x80x2]
and
[AAxe2x80x2],
wherein A and Axe2x80x2 are independently selected from the group consisting of 
wherein R1 is independently selected from the group consisting of hydrogen, C1 through C12 straight chain or branched alkyl, C3 through C12 cycloalkyl, aryl, and trifluoroethane;
R2 and R3 are independently selected from the group consisting of hydrogen, C1 through C12 straight chain or branched alkyl, C3 through C12 cycloalkyl, C1 through C12 alkoxy, F, Cl, SO3, C1 through C12 perfluoroalkyl, and N(CH3)2;
Z is selected from the group consisting of non-substituted C1 through C12 straight chain or branched alkyl, C3 through C12 cycloalkyl; methoxy; amino; halo; and C1 through C12 haloalkyl substituted straight chain or branched alkyl or cycloalkyl of up to 12 carbon atoms or C1-C40 aryl or alkylaryl groups.
X1 and X2 are independently selected from the group consisting halogens, hydride, triflate, acetate, trifluoroacetate, tris ([perfluorotetraphenyl) borate, and tetrafluoro borate, C1 through C12 straight chain or branched alkyl or alkoxy, C3 through C12 cycloalkyl or cycloalkoxy, and aryl or any other ligand with which a monomer can insert;
Accordingly, some of the ligands of the present invention have the structures: 
For compactness, some bonds are shown without termination; these bonds are terminated by methyl groups.
The metal M is selected from Cu, Ag, and Au. Among Cu, Ag, and Au, Cu is preferred; among X1 and X2, halogens are preferred.
Suitable non-halide X1 and X2 include triflate, tifluoroacetate, tris perfluorotetraphenyl borate, or tetrafluoro borate, hydride, alkyl groups or any other ligand into which a monomer can insert. Among the metal complexes of the present invention, those having the 1,1xe2x80x2bis(1-methylbenzimidazol-2yl)1xe2x80x3 methoxyethane ligand or the 3,3xe2x80x2(1-ethylbenzimidazol-2yl) pentane ligand, or 2,2xe2x80x2bis[2-(1-alkylbenzimidazol-2yl)] biphenyl, where the alkyl group is from C1-C20, and X1 =X2=chloride are particularly preferred.
1,1xe2x80x2bis(1-methylbenzimidazol-2yl)1xe2x80x3 methoxyethane ligands with copper as the metal and chlorine as X1 and X2 have the structure 
3,3xe2x80x2(1-ethylbenzimidazol-2yl) pentane ligands with copper as the metal and chlorine as X1 and X2 have the structure 
2,2xe2x80x2bis[2-(1-alkylbenzimidazol-2yl)]biphenyl ligands with copper as the metal and chlorine as X1 and X2, and C1-C20 as R1, have the structure 
Advantageously, the catalysts used to form the present invention are not poisoned by compounds containing hydrocarbyl polar functional groups when used in the formation of polymers and copolymers synthesized all or in part from olefinic monomers. As such, the catalysts of the present invention are useful in preparing polymers and copolymers formed from olefinic monomers, such as polyethylene; polymers and copolymers formed from monomers containing hydrocarbyl polar functional groups such as poly(methyl methacrylate); and copolymers derived from olefins and monomers containing hydrocarbyl polar functional groups such as poly (ethylene-co-methyl methacrylate).
A process used to form the present invention employs a metal complex having the formula LMX1X2, (wherein L, M, X1, and X2 are as previously defined) in combination with an activating cocatalyst. Examples of such activating cocatalysts include aluminum compounds containing an Alxe2x80x94O bond such as the alkylalumoxanes such as methylalumoxane (xe2x80x9cMAOxe2x80x9d) and isobutyl modified methylalumoxane xe2x80x9cdryxe2x80x9d MAO; aluminum alkyls; aluminum halides; alkylaluminum halides; Lewis acids other than any of the foregoing list; and mixtures of the foregoing can also be used in conjunction with alkylating agents, such as methyl magnesium chloride and methyl lithium. Examples of such Lewis acids are those compounds corresponding to the formula: Rxe2x80x3xe2x80x33B, or R3xe2x80x3xe2x80x3Al wherein Rxe2x80x3xe2x80x3 independently each occurrence is selected from hydrogen, silyl, hydrocarbyl, halohydrocarbyl, alkoxide, aryloxide, amide or combinations thereof, said Rxe2x80x3xe2x80x3 having up to 30 nonhydrogen atoms.
It is to be appreciated by those skilled in the art, that the above formula for the preferred Lewis acids represents an empirical formula, and that many Lewis acids exist as dimers or higher oligomers in solution or in the solid state. Other Lewis acids which are useful in the catalyst compositions of this invention will be apparent to those skilled in the art.
Other examples of such cocatalysts include salts of group 13 element complexes. These and other examples of suitable cocatalysts and their use in organometallic polymerization are discussed in U. S. Pat. No. 5,198,401 and PCT patent documents PCT/US97/10418 and PCT/US96/09764, all incorporated by reference herein.
Preferred activating cocatalysts include trimethylaluminum, triisobutylaluminum, methylalumoxane, alkyl modified alumoxanes, xe2x80x9cdryxe2x80x9d aliumoxanes, chlorodiethyaluminum, dichloroethylaluminum, triethylboron, trimethylboron, triphenylboron and halogenated, especially fluorinated, triaryl boron and aluminum compounds, carboranes and halogenated carboranes.
Most highly preferred activating cocatalysts include triethylaluminum, methylalumoxane, and fluoro-substituted aryl boranes and borates such as tris(4-fluorophenyl)boron, tris(2,4-difluorophenylboron), tris(3,5-bis(trifluoromethyl-phenyl) boron, tris(pentafluorophenyl) boron, pentafluorophenyl-diphenyl boron, and bis(pentafluorophenyl) phenylboron and tetrakis (pentafluorophenyl) borate. Such fluoro-substituted arylboranes may be readily synthesized according to techniques such as those disclosed in Marks, et al., J. Am. Chem. Soc., 113, 3623-3625 (1991). Fluorinated tetraaryl borates or aluminates and perfluoro tetranapthyl borates or aluminates, are also well known in the art.
The catalyst can be utilized by forming the metal complex LMX1X2 and where required combining the activating cocatalyst with the same in a diluent. The preparation may be conducted in the presence of one or more addition polymerizable monomers, if desired. Preferably, the catalysts are prepared at a temperature within the range from xe2x88x92100xc2x0 C. to 300xc2x0 C., preferably 0xc2x0 C. to 250xc2x0 C., most preferably 0xc2x0 C. to 100xc2x0 C. Suitable solvents include liquid or supercritical gases such as CO2, straight and branched-chain hydrocarbons such as isobutane, butane, pentane, hexane, heptane, octane, and mixtures thereof; cyclic and alicyclic hydrocarbons such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, halogenated hydrocarbons such as chlorobenzene, and dichlorobenzene perfluorinated C4-10 alkanes and aromatic and alkyl-substituted aromatic compounds such as benzene, toluene and xylene. Suitable solvents also include liquid olefins which may act as monomers or comonomers including ethylene, propylene, butadiene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene, and 4-vinycylohexane, (including all isomers alone or in mixtures). Other solvents include anisole, methylcbloride, methylene chloride, 2-pyrrolidone and N-methylpyrrolidone. Preferred solvents are aliphatic hydrocarbons and aromatic hydrocarbon, such as toluene.
It is believed that the cocatalyst interacts with the catalyst to create a polymerization-active, metal site in combination with a suitable non-coordinating anion. Such an anion is a poor nucleophile, has a large size (about 4 Angstroms or more), a negative charge that is delocalized over the framework of the anion, and is not a strong reducing or oxidizing agent [S. H.
Strauss, Chem. Rev. 93, 927 (1993)]. When the anion is functioning as a suitable non-coordinating anion in the catalyst system, the anion does not transfer an anionic substituent or fragment thereof to any cationic species formed as the result of the reaction.
The equivalent ratio of metal complex to activating cocatalyst (where employed) is preferably in a range from 1:0.5 to 1:104, more preferably from 1:0.75 to 1:103. In most polymerization reactions the equivalent ratio of catalyst:polymerizable compound employed is from 10xe2x88x9212: to 10xe2x88x921:1, more preferably from 10xe2x88x929:1 to 10xe2x88x924:1.
The catalysts used to prepare the present invention have a tetrahedral or pseudo-tetrahedral structure. It is believed that this structure is present when the catalyst is in the form of an isolated solid compound and when the catalyst is used in the presence of activating cocatalysts of this invention under homopolymerization or copolymerization conditions.
Olefinic monomers useful in the forming homo and copolymers with the catalyst of the invention include, for example, ethylenically unsaturated monomers, nonconjugated dienes, and oligomers, and higher molecular weight, vinyl-terminated macromers. Examples include C2-20 olefins, vinylcyclohexane, tetrafluoroethylene, and mixtures thereof. Preferred monomers include the C2-10 xcex1-olefins especially ethylene, propylene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene or mixtures of the same.
Monomers having hydrocarbyl polar functional groups useful in forming homo and copolymers with the catalyst of the invention, are vinyl ether and C1 to C20 alkyl vinyl ethers such as n-butyl vinyl ether, acrylates, such as C1 to C24, or alkyl acrylates such as t-butyl acrylate, and lauryl acrylate, as well as methacrylates such as methyl methacrylate.
In general, the polymerization may be accomplished at conditions well known in the prior art for Ziegler-Natta or Kaminsky-Sinn type polymerization reactions, that is, temperatures from xe2x88x92100xc2x0 C. to 250xc2x0 C. preferably 0xc2x0 C. to 250xc2x0 C., and pressures from atmospheric to 2000 atmospheres (200 Mpa). Suitable polymerization conditions include those known to be useful for metallocene catalyst when activated by aluminum or boron-activated compounds. Suspension, solution, slurry, gas phase or other process condition may be employed if desired. The catalyst may be supported and such supported catalyst may be employed in the polymerizations of this invention. Preferred supports include alumina, silica, and polymeric supports.
The polymerization typically will be conducted in the presence of a solvent. Suitable solvents include those previously described as useful in the preparation of the catalyst. Indeed, the polymerization may be conducted in the same solvent used in preparing the catalyst. Optionally, of course, the catalyst may be separately prepared in one solvent and used in another.
The polymerization will be conducted for a time sufficient to form the polymer and the polymer is recovered by techniques well known in the art and illustrated in the examples hereinafter. Of course care must be exercised otherwise some of the functional groups may be partially hydrolyzed upon work-up.